The manufacturers of Wankel rotary engines have attempted to provide an internal combustion engine that overcomes most of the drawbacks of a reciprocating piston engine, while operating very smoothly and having a high power to weight ratio and a higher rotational speed with respect to a reciprocating piston engine. After many years of Wankel engine development, there are some practical limitations that prevent its widespread acceptance, despite its theoretical advantages with respect to a reciprocating piston engine. Consequently, only a limited number of manufacturers are involved with Wankel engine production.
A typical prior art Wankel rotary engine is illustrated in FIG. 1, and is designated by numeral 10. A Wankel rotary engine 10 comprises rotor housing 101, rotor 102, spark plug 103, apex seal 104, eccentric shaft 105, stationary gear 106, rotor gear 107, exhaust port 108, inlet port 109. The minor axis of the trochoidal shape of the rotor housing is 110 and the major axis of the housing is 111. Each of the three faces A, B, and C of rotor 102 is involved sequentially with the following four cycles: intake cycle, compression cycle, power cycle and exhaust cycle. Fresh mixture is drawn through inlet port 109 by face A of the rotor 102 until it is at a peak volume. At the same time, face B is driven by the combustion forces and face C forces out the exhaust gas through the exhaust port 108.
Some of the Wankel rotary engine limitations relate to its rotor apex seals, as expressed by the following characteristics:                Tendency to bounce over housing internal contour;        Incompatibility of a suitable material for the apex seal with that of the rotor housing;        Damage to the internal contour of the rotor housing and to the seals;        Speed limitations due to high centrifugal forces;        Poor sealing at a low rotational speed and under sudden changes of operational conditions such as acceleration and deceleration and of engine load; and        Sealing limitations of the apex seal when the engine is exposed to a relatively high pressure, which is characteristic of Diesel engines.        
All of the above-mentioned limitations result in inadequate sealing that leads to low reliability and short duration of operation, defined also as a short time between overhauls (TBO).
Other known drawbacks of prior art Wankel rotary engines are:                The combustion chamber is not optimally configured for its function, and is therefore one of the main reasons for its inability in achieving efficient combustion and for its relatively low thermal efficiency.        A tendency to mix intake charge with burnt exhaust gases during exhaust-intake overlap, which reduces engine efficiency and output. The utility of a turbocharger, which further mixes the intake charge with the exhaust gases, is reduced since a greater percentage of the burnt gas is forced thereby to remain in the engine, to drift by the motor rotor to the intake section thereof, and to mix with the intake charge.        A high surface to volume ratio, resulting in fuel condensation on the inner walls of the working volumes, which is particular noticeable in water-cooled engines and negatively influences efficiency and wear.        At the beginning of each work cycle, a noticeable conflict is characteristic of prior art Wankel engines resulting in inefficient utilization of combustion products, between the geometrical position of the rotor during ignition to the direction of the driving forces generated by the combustion products. At ignition, the leaning angle of the rotor (i.e., the angle of inclination of a line coincident with the seal and the engagement point of the stator and rotor gears with respect to the minor axis of the rotor housing) bisects the two opposed rotational directions of the expansion forces generated by the burnt gases, resulting in a combustion force opposing the rotational direction of the rotor to be of a magnitude substantially equal to that of the combustion force supporting the rotation of the rotor. As the rotor rotates and the leaning angle changes, the magnitude of the combustion force supporting the rotation of the rotor correspondingly increases such that it is of a magnitude significantly greater than that which opposes the rotational direction of the rotor. When the leaning angle is approximately 60 degrees, substantially all of the combustion forces support the rotation of the rotor; however, the remaining pressure of the combustion products is very low at such a leaning angle indicating that the work cycle is about to end.        In addition to the previously mentioned conflict, substantially all of the combustion pressure is generated, immediately after ignition, over the rotor and perpendicularly to the main shaft, imposing a very high load and stress to the engine system which must be taken into consideration during the engine system design.        The effective work cycle sector of prior art Wankel engine is considerably narrow, beginning after an apex of the rotor has passed the minor axis by about 60 degrees and ending after about 60 degree of rotation, where the same apex reaches the point which start to expose the exhaust port.        The compression ratio of prior art Wankel rotary engine depends on the K factor (defined as ratio of the rotor radius to eccentricity). A lower K factor allows for a smaller engine for a given displacement; however, its potential compression ratio is low and apex seal leaning angle is very high, as the apex seals must pass over a very tight housing contour at the minor axis lobes of the rotor housing. As the K factor getting increases, the engine size and the potential compression ratio increase for a given displacement, while the apex seal leaning angle decreases. In order to achieve reasonably good results with a prior art Wankel engine, limiting compromises must be made.        The eccentric motion of the rotor drive system assembly of the Wankel engine results in restrictions to engine speed, and poses dynamic balancing problems. The complex motion of the rotor and the eccentric shaft assembly results in a shaft speed three times higher than that of the rotor, thereby resulting in a low torque-high speed engine shaft power take off (P.T.O.)        
Despite the aforementioned disadvantages, the Wankel rotary engine provides some significant characteristics which result in its attractiveness to various relevant industries. A suitable solution to the aforementioned disadvantages can provide a Wankel rotary engine with superiority over most reciprocating piston engines, and in certain embodiments, even over some gas turbine applications.
Therefore, it is an object of the present invention to provide an improved combustion engine that is suitable for land, marine and aviation propulsion, as well as for stationary pumping, electrical power and other domestic and industrial applications.
It is another object of the present invention to provide a rotary engine system with a bouncing free sealing method.
It is another object of the present invention to provide a rotary engine with an effective sealing method that is also less sensitive to material matching and is not affected by engine velocity.
It is another object of the present invention to provide a sealing system that does not damage the internal contour of the rotor housing and enables a higher operating pressure.
It is another object of the present invention to provide a method for shaping a compact and effective, controllable, combustion chamber.
It is another object of the present invention to provide a method for a compact, effective, and controllable, combustion chamber which is also a variable compression-ratio device that can automatically change the compression ratio during operation, in accordance with operational condition such as air density (altitude), ambient temperature and load.
It is another object of the present invention to provide a method of operation that completely scavenges exhaust gases and eliminates the mixing of intake charge with exhaust gases.
It is another object of the present invention to provide a rotary engine which employs a turbocharger without any negative influences on engine scavenging and the mixing of the intake charge with exhaust gases and therefore has increased output power and an improved power to weight ratio as well as an improved density compensation.
It is another object of the present invention to provide a rotary engine that eliminates fuel condensation on internal volume walls.
It is another object of the present invention to provide a rotary engine in which, geometrically, substantially all of the combustion pressure operates in the rotational direction from the beginning to the end of the work cycle.
It is another object of the present invention to provide a rotary engine that operates at a much wider working sector in comparison with the prior art Wankel engine and as a result, achieves a higher output and higher efficiency.
It is another object of the present invention to provide a rotary combustion engine that can efficiently burn a broad range of fuels.
It is another object of the present invention to provide a combustion rotary engine with low sensitivity to altitude (density compensated) for the benefit of aviation applications.
It is yet another object of the present invention to provide an improved, fully rotational, concentric, system, in contrast with the eccentric system of a Wankel engine, and to integrate such a concentric system with the additional improvements provided by the present invention.
It is yet another object of the present invention to provide a combustion engine system that is cost effective.
It is yet another object of the present invention to provide a rotary engine system that overcomes the disadvantages of the prior art devices while retaining their inherent advantages.
Other objects and advantages of the present invention will become apparent as the description proceeds.